Many security and safety personnel, such as police, fire fighters and ambulance drivers use radio systems for communication. Radio frequencies are allocated based on the agency to which the safety and security team belongs and on their geographical location. For example, the Palo Alto police department may use one set of radio frequencies while the San Jose police department may utilize a different set of frequencies. This method allows each team to use their radio to broadcast communications to their own team without overwhelming a neighboring team with information which may not be relevant for their operations. In addition, this method enables the reuse of the limited frequency bands for communication by other teams.
Statewide agencies like the California Highway Patrol (CHP) or nationwide agencies like the Federal Bureau of Investigation (FBI) may need to communicate with local safety and security agencies as part of their normal operations. For example, if the CHP needs to chase a car on highway a certain highway, they may need to coordinate the event with the local agencies along the chase path. Some systems rely on a centrally located dispatch to coordinate communication with local agencies. Some systems rely on a handbook of frequencies for different agencies at a variety of locations. In addition, some safety and security personnel utilize frequency scanners to locate the set of frequencies utilized in specific geographical locations. Many communications over such frequencies are increasingly becoming encrypted.